It is known that electrical characteristics of circuit components, whether discrete or integrated, are frequently sensitive to and variable with temperature. It has accordingly been known in the prior art to try to stabilize operational characteristics and electrical parameters of electronic circuits by attempting to maintain a relatively constant ambient temperature for the circuit.
Typically, electrical parameters of circuit components, such as resistors, are measured at and remain substantially constant at known, constant, temperatures. It is thus known to operate a circuit at a predetermined temperature to maintain the electrical characteristics thereof at fixed values. However, temperature control and stabilization has previously been expensive to implement because of the need for additional circuitry and the increased space requirements therefor.
Difficulties encountered in prior art efforts to attain temperature stabilized operation have often related to obtaining an arrangement of the electronic circuit to be stabilized together with apparatus for controlling the ambient temperature. Additionally, and more specifically, it has been difficult to combine the circuit to be controlled with specific heating apparatus to provide the desired operating temperature.
Accordingly, in the prior art it has become accepted to control the ambient temperature of a circuit by enclosing the circuit within an oven structure.
Such a prior art approach, however, is expensive and thus tends to discourage operation of electronic circuits at desired temperatures. In addition to requiring the heat generating circuitry, the prior art temperature control arrangements require an enclosure. Such enclosures, even if limited to surround a particular circuit board or arrangement, add both to the expense of fabricating the device and to the space and volume required thereby.
Accordingly, temperature stabilized operation has been unavailable in inexpensive electronic circuits and devices. The precision available by operation of electrical circuits at known and controlled temperatures has been relegated to more expensive devices and has been generally unavailable in less expensive devices, such as used in consumer electronics.
There has thus been a need in the prior art for easily implemented and inexpensive temperature control arrangements for electronic circuits. More specifically, there has been a need for heat generating and heat control circuits which do not require expensive ovens or excessive space and volume for implementation.